Purpose Driven Design for Waste Heat Recovery

Robert Thompson, SmithGroupJJR, Inc.

ASHRAE Standard 90.1 functions as a baseline to ensure that new buildings meet minimum energy performance goals. This standard is continuously updated to increase the overall building energy performance. Manufacturers respond by enhancing system energy efficiency through the reduction of losses, performance improvements, and advancements in controls. Architects and engineers look to optimize performance through building orientation, shading, and climate-specific design. This approach to building design has decreased the energy use intensity (EUI) of a typical office building from a high of 100 kBTU/SF/Year in 1995 to 67 kBTU/SF/Year in 2014, a 33% improvement.

Waste heat recovery, in its various forms, has long been a staple of the ASHRAE Standard 90.1. The most common form of waste heat recovery is found in mechanical systems with high outside air loads. In these systems, a significant amount of energy is used to condition outside air. Instead of throwing this energy away, a portion of the energy within the "exhaust" stream can be used to pre-condition outside air. While office systems my recover both sensible (thermal) and latent (moisture) energy, laboratory systems are limited to sensible energy recovery only due to cross-contamination concerns. Other waste heat recovery systems are water-based, using waste heat from a process to preheat other building systems.

There is the potential for additional energy savings, however, by combining complementary building programs within the same facility or campus. Serving offices and laboratories from a common HVAC system, where permitted, reduces the ventilation required, which in turn saves energy. Mechanical systems with large amounts of waste heat, when combined with large outside air demands in a predominantly heating environment, benefit from reduced or minimal heating demands.

The Department of Energy's (DOE) National Renewable Energy Laboratory's (NREL) Energy Systems Integration Facility (ESIF) in Golden, Colorado was R&D Magazine's Laboratory of the Year in 2014, and is an example of purpose driven waste heat recovery. This facility uses waste heat recovery, in the form of hot water from the high performance computing data center to provide heating for offices and laboratory outside air. We will step through the process of identifying functions and systems, making the best use of waste heat recovery at the NREL ESIF facility.

The goal of this presentation is to help owners, architects, and engineers identify opportunities for improved building performance and waste heat recovery on their own projects.

Learning Objectives

  • Become familiar with the provisions within ASHRAE 90.1 regarding waste heat recovery and the resources available through the Labs21 Benchmarking Tool.
  • Understand the concept and the various forms of waste heat recovery as it relates to building systems for a variety of space types.
  • Identify complementary programs or spaces within a building (or campus) that can enhance the effectiveness of waste heat recovery systems.
  • Understand the process of purpose driven waste heat recovery as it relates to the Department of Energy's (DOE) National Renewable Energy Laboratory's (NREL) Energy Systems Integration Facility (ESIF) in Golden, Colorado. This facility utilizes waste heat from its data center to provide beneficial heating within the building and to NREL's campus.


Robert Thompson is a registered professional engineer and chief mechanical engineer for the Science & Technology studio in the Phoenix office. Robert's designs focus on the environmental design specifics that influence the energy & sustainable performance of buildings. Recent work includes the Department of Energy's (DOE) National Renewable Energy Laboratory's (NREL) Energy Systems Integration Facility (ESIF) in Golden, CO and Augustana University's Froiland Science Center in Sioux Falls, SD.


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